Cisco IOS

Before using this scanner it is recommended that you lower the ARP cache timeout on your router, as Cisco IOS normally comes with a 4 hour default ARP cache timeout.

For example, the following commands will lower the timeout to 2 minutes on Vlan1:

# 1. use this command to see what Vlan your devices are on
show ip arp
# 2. Go into configure mode
conf t
# 3. Use the Vlan name as you see it from step 1 above
interface Vlan1
# 4. Set a new arp cache timeout
arp timeout 120
# 5. Exit# Press <ctrl+c> to exit configure mode# 6. Don't forget to save the new config, so that it will survive a reboot
copy running-config startup-config

If you have a very large number of devices on your VLan (+1000), then you may want to adjust the ARP cache timeout to suit your needs. See this discussion to learn more.

To use this device tracker in your installation, add the following to your configuration.yaml file: